Hey there. I'm not exactly sure what you intend on using it for, but I'll let you know about my experience so far with the Surface 4 Pro.
I have a Surface 4 Pro with an i5 processor and 128GB storage - it's essentially the mid-range Surface 4 Pro model. I've found it incredibly easy to use and the screen is absolutely gorgeous. My only real issue with it is the touchscreen - with some apps, they are not exactly 'optimized' for such a small screen/high resolution, so some buttons take a few attempts to 'hit' if you're using the touchscreen aspect of it (since some buttons are very small due to the high resolution) - I usually just use the pen for any kind of specific pointing.
Otherwise, I'm absolutely in love with the machine. The sound quality and video quality is phenomenal, the responsiveness is amazing, and the versatility is hard to beat - you can either use it as a standard tablet, as a tablet + stylus, or as a laptop with the type cover. The pen is great, it attaches to the Surface magnetically, it has an eraser, the palm-block technology they use is wonderful, so is their handwriting and speech recognition.
I'd have to say it's probably the best money I've spent for a mobile computer, but it really depends on the context in which you need to use it. I've used it for playing games like Hearthstone and taking care of all my university needs.
Good luck in your search!